Visualization of Flow Patterns

1. A system for visualizing a flow within a volume of a 3-dimensional (3-D) image, the system comprising: a first transfer unit configured to apply a first transfer function, wherein the first transfer function assigns a renderable property to each location of a first plurality of locations within the volume of the 3-D image based on a flow pattern class assigned to each location of the first plurality of locations, the flow pattern class being assigned from a plurality of flow pattern classes for classifying the flow at each location of the first plurality of locations; a second transfer unit configured to apply a second transfer function, wherein the second transfer function assigns a renderable property to each location of a second plurality of locations within the volume of the 3-D image based on a value of the 3-D image assigned to each location of the second plurality of locations; and a mixing unit configured to compute a first 2-dimensional (2-D) image based on the renderable property assigned to each location of the first plurality of locations and a second 2-D image based on the renderable property assigned to each location of the second plurality of location, the mixing unit being configured to compute the first 2-D image and the second 2-D image for displaying on a display by rendering using the renderable properties assigned by the first and second transfer functions, the mixing unit being further configured to display the first and second 2-D images alternatingly for a predetermined period of time, wherein the plurality of flow pattern classes are defined by ranges of curvature and torsion values, each of the plurality of flow pattern classes having a different range of curvature and torsion values, and wherein the flow pattern class assigned to each location of the first plurality of locations is assigned directly based on curvature and torsion values calculated for each location of the first plurality of locations.

2. The system of claim 1 , wherein the mixing unit is further configured to compute a renderable property at each location of a third plurality of locations within the volume based on the renderable property assigned to each location of the first and second plurality of locations, and wherein the mixing unit is further configured to compute at least one of the first 2-D image and the second 2-D image based on the renderable property computed at each location of the third plurality of locations.

3. The system of claim 1 , further comprising a pattern classification unit configured to compute the flow pattern class at each location of the first plurality of locations.

4. The system of claim 1 , wherein the renderable property assigned to each location of the first or second locations comprises a color and at least one of an opacity and transparency.

5. The system of claim 1 , further comprising a user interface configured to receive a user input for defining at least one of the first and second transfer function.

6. The system of claim 1 , wherein the first transfer unit is configured to apply the first transfer function independently of the second transfer function applied by the second transfer unit.

7. The system of claim 1 , wherein the first transfer unit is configured to apply the first transfer function concurrently with the second transfer function applied by the second transfer unit.

8. The system of claim 1 , wherein the mixing unit is further configured to blend the renderable property assigned to each location of the first plurality of locations with the renderable property assigned to each location of the second plurality of locations resulting in blended renderable properties, and wherein direct volume rendering is used to compute the 2-D image based on the blended renderable properties.

9. The system of claim 1 , wherein the renderable property assigned to each location of the first plurality of locations within the volume of the 3-D image and the renderable property assigned to each location of the second plurality of locations within the volume of the 3-D image are merged together by the mixing unit by adding corresponding renderable properties of the first and second plurality of locations resulting in resulting renderable properties, and wherein the mixing unit is configured to compute at least one of the first 2-D image and the second 2-D image based on the resulting renderable properties.

10. A workstation comprising a system as claimed in claim 1 .

11. An image acquisition apparatus comprising a system as claimed in claim 1 .

12. A method of visualizing a flow within a volume of a 3-dimensional (3-D) image, the method comprising acts of: applying a first transfer function by a first transfer unit, wherein the first transfer function assigns a renderable property to each location of a first plurality of locations within the volume of the 3-D image based on a flow pattern class assigned to each location of the first plurality of locations, the flow pattern class being assigned from a plurality of flow pattern classes for classifying the flow at each location of the first plurality of locations; applying a second transfer function by a second transfer unit, wherein the second transfer function assigns a renderable property to each location of a second plurality of locations within the volume of the 3-D image based on a value of the 3-D image assigned to each location of the second plurality of locations; and computing a by a mixing unit first 2-dimensional (2-D) image based on the renderable property assigned to each location of the first plurality of locations and a second 2-D image based on the renderable property assigned to each location of the second plurality of locations, the mixing unit being configured to compute the first 2-D image and the second 2-D image for displaying on a display by rendering using the renderable properties assigned by the first and second transfer functions, the mixing unit being further configured to display the first and second 2-D images alternatingly for a predetermined period of time, wherein the plurality of flow pattern classes are defined by ranges of curvature and torsion values, each of the plurality of flow pattern classes having a different range of curvature and torsion values, and wherein the flow pattern class assigned to each location of the first plurality of locations is assigned directly based on curvature and torsion values calculated for each location of the first plurality of locations.

13. The method of claim 12 , further comprising an act of computing the flow pattern class at each location of the first plurality of locations by a pattern classification unit.

14. A non-transitory computer readable medium comprising computer instructions which, when executed by a processor, configure the processor to perform a method of visualizing a flow within a volume of a 3-dimensional (3-D) image by performing acts of: causing application of a first transfer function by a first transfer unit; wherein the first transfer function assigns a renderable property to each location of a first plurality of locations within the volume of the 3-D image based on a flow pattern class assigned to each location of the first plurality of locations, the flow pattern class being assigned from a plurality of flow pattern classes for classifying the flow at each location of the first plurality of locations; causing application of a second transfer function by a second transfer unit, wherein the second transfer function assigns a renderable property to each location of a second plurality of locations within the volume of the 3-D image based on a value of the 3-D image assigned to each location of the second plurality of locations; and causing computation of a first 2-dimensional (2-D) image based on the renderable property assigned to each location of the first plurality of locations and a second 2-D image based on the renderable property assigned to each location of the second plurality of locations; causing a display to display the first 2-D image and the second 2-D image by rendering using the renderable properties assigned by the first and second transfer functions, and to display the first and second 2-D images alternatingly for predetermined period of time, wherein the plurality of flow pattern classes are defined by ranges of curvature and torsion values, each of the plurality of flow pattern classes having a different range of curvature and torsion values, and wherein the flow pattern class assigned to each location of the first plurality of locations is assigned directly based on curvature and torsion values calculated for each location of the first plurality of locations.